Ludwigia uruguayensis (Camb.) Hara

Ludwigia uruguayensis (Camb.) Hara
Uruguay Waterprimrose, Showy Waterprimrose

Category
Aquatic

Description

Perennial plant with preference for sluggish streams, pools, and marshes.

Stem

Stems are sometimes hairy and by late in the growing season become reddish and woody. Roots branch from the lower nodes of the stems in water and give the plant a feathery appearance. Plants can grow to 3 ft. (1 m) high or up to 6 ft. (1.8 m) long when floating on water. When growing in mud or dense mats, white, spongy roots often grow from the nodes.

Leaves

Willowlike, lance-shaped leaves grow alternately along the stems, 4.5 in. (11.2 cm) long and 0.5 to 1 in. (1.3 to 2.5 cm) wide, becoming very crowded near the tip of the stem. Woody seed capsules growing to 1.5 in. (3.7 cm) long hang on stalks from the leaf axils.

Flowers

Showy, yellow, 5-petaled flowers up to 1 in. (2.5 cm) across bloom all summer. Flowers grow on short stalks from the leaf axils. Before flowering, a cluster of spoon-shaped leaves grows on the surface of the water. Stems and leaves elongate as plants prepare to flower.

Fruit

Pubescent capsule with many seeds.

Life History

Habitat

Creeping water primrose occurs in freshwater along lake, pond, and river edges from New York south to Florida, west to Texas and also in California and the Pacific Northwest. Tends to prefer waterways with slow moving, nutrient-enriched water. It may be native to parts of the southeastern United States, but is classified by several of these states as a noxious weed.

Origin and Distribution

Uruguay water primrose can be found in the following states: USA (AL, AR, CA, DC, FL, GA, KY, LA, MO, MS, NC, NJ, NY, OK, OR, PA, SC, TN, TX, VA, WA, WV)

Synonyms

Jussiaea grandiflora Michx., non Ruiz & Pav.
Jussiaea michauxiana Fernald, nom. illeg.
Jussiaea repens L. var. grandiflora (Michx.) Micheli
Jussiaea uruguayensis Camb.
Ludwigia uruguayensis (Camb.) H. Hara
Ludwigia uruguayensis (Camb.) H. Hara var. major (Hassler) Munz

h2. Management Recommendations

Mechanical Controls

Carefully remove any seed heads and bag them securely in plastic bags. Bagged seed heads are best incinerated, to avoid further seed spread. Great care should be taken not to inadvertently spread seed that has attached to clothing. Seedlings can be hand pulled or mechanically pulled with equipment, but larger plants will re-shoot unless the majority of the many long embedded roots are removed. Also, discarded plants left lying on soil may take root. One must always follow up the treatment by rechecking the area for any regrowth and new seedlings

Herbicidal Controls

Use of glyphosate and a non-oil sticking agent (or other aquatics approved surfactant/adjuvant) as a foliar treatment for prolonged slow release of the herbicide into the plant causes high rates of mortality.

Biological Controls

A flea beetle, Lysathia flavipes, causes heavy damage and sometimes mortality to L. peploides plants in its native Argentina. The adult and larvae feed on, and eggs are laid on, the leaves of both L. peploides and parrot’s feather, Myriophyllum aquaticum. Further research is needed for biocontrol.

Bibliography

Kaufman S.R. and Kaufman W. 2007. Invasive Plants: Guide to Identification and the Impacts and Control of Common North American. Stackpole Books, Mechanicsburg, PA. 414 pp.

USDA

Sydney Weeds Committees. Undated. Ludwigia peruviana. Noxious Weed Category: W2

Army Corps of Engineers, The Wild Classroom, Weedy Plants of the U.S., Exotic, Invasive, and Problem Plants, "Uruguayan Primrose":http://www.thewildclassroom.com/biodiversity/problemplants/species/Uruguayan%20Primrose.htm

Cordo, H.A. and C.J. DeLoach. 1982. The flea beetle, Lysathia flavipes, that attacks Ludwigia (water primrose) and Myriophyllum (parrot feather) in Argentina. The Coleopterists Bulletin 36(2): 298-301.

Pillsbury, D. (2005) Outbreak of mosquitoes raises possible threat of West Nile Virus. Sonoma West Times & News. 20 Jan. 2003. Archives. 10 October